Cell phone carriers operating Internet Protocol (IP) Multimedia Subsystem (IMS) networks are introducing new services to wireless subscribers. One service, known as Advanced Call Feature (ACF), enables a user equipment (e.g., mobile phone, laptop, tablet, etc.) to make Voice over LTE (VoLTE) phone calls. VoLTE uses IP packets to support voice calls, potentially offering much higher quality calls and faster set-up times, among other things, than traditional 2G services that provide circuit-switched voice calls.
However, the quality and availability of VoLTE is determined by the quality of the coverage of the local LTE network. This means that a user equipment (UE) that is connected to an LTE network in a weak coverage area may attempt a VoLTE call even though the network conditions may not be sufficient to give the end-user the same good experience the mobile phone subscriber may be accustomed to with a legacy radio access technology (RAT), such as CDMA 1×RTT. This can result in dropped calls, muted audio, and distorted audio, among other things. Additionally, this may cause the subscriber to blame the mobile phone for the poor quality of the phone call, rather than the LTE network conditions.
Therefore, there is a need in the art for systems and methods for offering Advanced Calling Feature (ACF) service to a mobile phone subscriber. In particular, there is a need for systems and methods that provide an improved VoLTE experience during periods of poor coverage in an LTE network.